Traditionally, there have been two types of biological systems which have been used to remove organic contaminants from waste waters. These are the fixed-film system, and the suspended growth, or activated sludge system. Each of these systems has their advantages and disadvantages which result in their being specifically used for different applications.
For example, the fixed-film systems are proven more effective than the activated sludge systems in handling hydraulic and organic shock loads. This is principally because the bacteria can affix themselves to the medium in a protective layer and propagate to provide an active biological system on the surface of the layer. On the other hand, the activated sludge systems are highly efficient on consistent waste water flows. However, they are very sensitive to hydraulic and organic loading changes.
The upflow biological reactor system combines the benefits of both a fixed-film system for toxic and hard to biodegrade materials and a suspended growth system for total breakdown of organic wastes.
Generally, such biological reactor systems comprise an influent or waste holding tank; nutrient feed system; the actual upflow aerobic biological reactor tower; and an effluent or settling tank.
The purpose of the present invention is to optimize the performance of an upflow biological reactor (UBR) system by making various improvements thereto which will permit it to perform more efficiently. Towards that end, the present invention proposes to first of all preoxygenate the waste water, enriching it with dissolved oxygen prior to its entry into the biological reactor tower. A unique apparatus to accomplish this is disclosed.
Further, the proposed improvement includes a unique distributing means disposed at the base of the biological reactor tower for delivering the preoxygenated waste water evenly across the entire horizontal cross-sectional area of the UBR. The improved distribution means inhibits the development of anaerobic conditions in the tower; and inhibits the crystallization or solidification of the waste in the UBR.
Further, the improved treatment system includes means for utilizing the oxygen which remains in the discharge air of the UBR for further oxygenation of any remaining waste in the system effluent tank. In addition, this part of the improvement to the treatment system provides for the condensation and containment of any foam which may be discharged from the UBR, and results in facilitating the agitation of the remaining waste so as to prevent it from going into an anaerobic state, thus preventing objectionable odors.